Work Aid 1A: Procedures That Are Used To Calculate The Required Control Valve Cv
1. Use the following ISA and Fisher equations to solve for Cv.
Fisher: C Q G P v= ∆ ISA: C q N G p p v = f − 1 1 2
To determine the appropriate value N1, refer to the table below.
Constant Units That Are Used In Equations
N w q p, ∆∆P d, D γγ1 νν
N1 0.0865 --- m3/h kPa --- --- ---
0.865 --- m3/hr bar --- --- ---
1 --- gpm psia --- --- ---
2. Refer to Fisher Catalog 10 or to other manufacturer's catalog and locate the appropriate pages for the valve types that are described in the Exercise. For each valve type, browse through the Cv table and locate a valve size that will provide the required capacity. Ensure that you select a valve size that will provide the required Cv at a percentage of travel that is consistent with the guidelines that are given in Section 5.2 of SAES-J-700. The guidelines are summarized in the table below.
Extrapolate the degrees of rotation or the percent of travel that provides the required Cv.
For rotary-shaft valves, convert the degrees of rotation to percent of travel by dividing the degrees of rotation that provide the required Cv by 90 degrees.
Guidelines For Percent Travel At Various Flow Conditions Per Section 5.2 of SAES-J-700 Flow Characteristic Percent Travel At NormalFlow Percent Travel At MaximumFlow
Equal Percentage 80 93
Linear 70 90
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Work Aid 1B: Procedures That Are Used To Calculate The Allowable Pressure Drop (∆Pallow)
Perform the following procedures to complete Exercise 1B.
1. Locate the required fluid properties from the Fisher Control Valve Handbook as follows:
SG Properties of Water table, page 135
Pv Properties of Water table, page 135 (given as Saturation Pressure) Pc Physical Constants of Various Fluids table, page 134
2. Using the following equation, calculate the ∆Pallow.
∆Pallow = Km (P1-rc Pv)
Locate the values that are required to solve the equation as follows:
Km Use the value that is listed in the Exercise under the heading "Valve Specifications."
P1 Use the value that is listed in the Exercise under the heading "Service Conditions."
Pv Use the value that was recorded during step 1. of this Exercise. rc Refer to Fisher Catalog 10, section 2, page 10, Figure 1.
3. Using the Fisher Sizing equation that is included in Work Aid 1A, calculate the required Cv. Use the lesser of the actual ∆P or the ∆Pallow.
Refer to the page in Fisher Catalog 10 that lists the Cv's for the selected valve and select the smallest valve size that will provide the required Cv at a percentage of travel that is consistent with the guidelines that are given in Section 5.2 of SAES-J-700 (refer to Work Aid 1A). Extrapolate and record the percent of travel at which the Cv requirements are met. Note and record the Km of the selected valve.
4. Using the value of Km that was determined in step 2, recalculate the ∆Pallow. 5. Using the new value of ∆Pallow, recalculate the required Cv.
6. Select a valve size that will meet the Cv requirements.
Work Aid 1C: Procedures That Are Used To Calculate The Effect Of Piping Factors On Cv
Perform the following procedures to complete Exercise 1C.
1. Locate the appropriate pages in Fisher Catalog 10 for the valve that is described in the Exercise. Ensure that you locate the page for the line-to-body size ratio that is given in the Exercise. Browse through the Cv column and locate a valve that provides the maximum Cv at less than the percent of travel guideline that is included in Section 5.2 of SAES-J-700. Note: For rotary valves, the percentages of travel that are listed in Section 5.2 of SAES-J-700 can be converted to degrees of rotation as follows:
% travel x 90 degrees
2. Refer to Section 5.4 of SAES J-700. Locate the value of R for the valve type that is described in the Exercise. Calculate the required Cv through use of the following equation:
Re quired Cv = Calculated Cv
R
Using the required Cv that was just calculated, refer to the appropriate page in Fisher Catalog 10, and select a valve size. Note: The required Cv has already been corrected; therefore, ensure that you select a valve size from the page for the 1:1 line-to-body size ratio. Also, ensure that the selected valve provides the maximum required Cv at a travel that is consistent with the guidelines that are listed in Section 5.2 of SAES-J- 700. (Refer to the note in step 1, above.)
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Work Aid 1D: Procedures That Are Used To Calculate The Effect Of Laminar Flow On Cv
Perform the following procedures to complete Exercise 1D.
1. Without attempting to compensate for fluid viscosity, calculate the required Cv for the application that is described. Use the following equation.
C Q G
P v =
∆
2. To compensate for viscous effects, locate the Viscosity Correction Nomograph in Fisher Catalog 10, Section 2, pages 26 and 27 and follow the instructions that are included in the nomograph. Use the value of Cv that was calculated in step 1.
Work Aid 2: Procedures That Are used to Computer size con trol valves for liquid Applications
Work Aid 2A: Procedures That Are Used To Computer Size Control Valves For Water Applications
1. Use the following procedures to complete part 1.
a. If necessary, press ESCAPE to return to the main menu. b. From the main menu, select Valve.
c. Press and hold the ALT key and press F5 to clear all sizing inputs. d. Select the Fisher Water method.
e. From the menu that appears, select the Cv Simple method.
f. Ensure that the engineering units on the calculation screen match the units that are used to describe the application. If the units do not match for any field, move the cursor to that field, press the F8 key, and select the desired units. Press ESCAPE.
g. Enter the pressure drop (dP). dP = P1 minus P2.
h. Locate the SG of water at 100 degrees F from the table on page 135 of the Fisher Control Valve Handbook. Enter the value of SG in the appropriate field. i. Enter the flow rate.
j. Press F2 to calculate the valve sizing information. Record the values that are requested in the Exercise.
2. Use the following procedures to complete part 2. a. Press ESCAPE.
b. Select the Valve Sizing and LpA option.
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• Cavitation Check OFF • Warnings OFF
d. Ensure that all of the fluid properties and the service conditions are accurately entered.
e. Enter an estimated value of Km. Select a value from the table below. Typical Values Of Km and FL
Valve Style Typical Km Typical FL
Globe And Angle 0.75 .87
Rotary-Shaft 0.45 0.67
f. Press F2 to calculate the valve sizing information. Record the values that are requested in the Exercise.
3. Use the following procedures to complete part 3. a. Press ESCAPE twice.
b. Select the Fisher Liquid method. c. Select the Valve Sizing and LpA option.
d. Press F3 and ensure that the Input Pv option is selected. e. Enter the value of Pv that was recorded during step 2 above.
f Obtain the value of Pc from the table on page 134 of the Control Valve Handbook
g. Ensure that all service conditions and fluid properties are accurately entered. h. Press F2 to calculate the valve sizing information. Record the values that are
requested in the Exercise.
4. Use the following procedures to complete part 4. a. Press ESCAPE twice.
b. Select the ISA Liquid method.
d. Determine an estimated value of FL through the use of the equation that follows or by selecting a value from the table below.
Estimated FL = Estimated Km Typical Values Of Km and FL
Valve Style Typical Km Typical FL
Globe And Angle 0.75 .87
Rotary-Shaft 0.45 0.67
e. Enter the estimated FL.
f. Ensure that all service conditions and fluid properties are accurately entered. g. Press F2 to calculate the valve sizing information. Record the values that are
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Work Aid 2B: Procedures That Are Used To Computer Size Control Valves For Choked Flow
Use the following procedures to complete Exercise 2B. 1. Return to the main menu.
2. From the main menu, select Valve.
3. From the menu that appears, select the Fisher Liquid method.
4. Press and hold the ALT key and press F5 to clear any sizing inputs. 5. Select the Valve Sizing and LpA option.
6. Press F3 and ensure that the option Input Pv is selected. 7. Enter the fluid name as "HC liquid."
8. Enter the fluid properties and the service conditions.
9. Enter the estimated Km. (Refer to the table in step 4 of Work Aid 2A.) 10. Press F2 to calculate the valve sizing information.
11. Refer to the appropriate page in Catalog 10 and select a valve size that will provide the maximum Cv at a percentage of travel that is consistent with the guidelines that are listed in Section 5.2 of SAES-J-700. (Refer to the table in Work Aid 1A).
12. Record the information that is requested under the heading "Initial Calculations and Valve Selection."
13. Using the Km of the initially selected, recalculate the valve sizing information. Note that the calculated Cv may now allow the selection of a smaller valve. To determine if a smaller valve will pass the required flow, use the Km of the smaller valve to recalculate the sizing information.
14. Record the information that is requested under the heading "Final Calculations and Valve Selection."
Work Aid 2C: Procedures That Are Used To Computer Size Control Valves For Fluids In The Sizing Database
1. Use the following procedures to complete part 1. a. Return to the main menu.
b. From the main menu, select Valve.
c. From the menu that appears, select the Fisher Liquid method.
d. Press and hold the ALT key and press F5 to clear any sizing inputs. e. Select the Valve Sizing and LpA option.
f. Press F3 and ensure that the option Input Pv is selected. g. Enter the fluid name as "Liquid Propane."
h. Refer to page 130 of the Fisher Control Valve Handbook, and locate the values of Pc, Pv, and SG for the liquid. Enter these values in the proper fields on the calculation screen. Note: The value of Pv that is included in the table is for the fluid at a temperature of 100 degrees F; however, this value of Pv will be used because it is the only value that is available.
i. Enter all of the service conditions.
j. Enter an estimated value of Km. (Refer to the table in part 4 of Work Aid 2A.) k. Press F2 to calculate the valve sizing information. Record the information that
is requested under the heading Calculated Results. 2. Use the following procedures to complete part 2.
a. Place the cursor on the appropriate fields and press the F5 key to clear the values that were previously entered for Pv and Pc.
b. Press F3 and select the Calculate Pv option.
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3. Use the following procedures to complete part 3.
a. Without clearing the calculation screen, change the temperature and the SG to to the values that are stated in part 3.
b. Press F2 to calculate the valve sizing information. Record the information that is requested under the heading Calculated Results.
4. Use the following procedures to complete part 4.
a. Without clearing the calculation screen, change the Km to 0.75.
b. Press the F2 key to calculate the valve sizing information. Record, under the heading Calculated Results on the Exercise Sheet, the information that is requested.
Work Aid 2D: Procedures That Are Used To Computer Size Control Valves With Piping Factor Correction
1. Use the following procedures to complete part 1.
a. Press ESCAPE to return to the menu that gives choices of sizing methods. b. Select the Fisher Water sizing method.
c. Press and hold the ALT key, and press the F5 key to clear all sizing inputs. d. Select the Valve Sizing and LpA option.
e. Press F3. Ensure that the option Calculate SG is selected. f. Enter the service conditions.
g. Enter an estimated value of Km. (To determine an estimated Km, refer to the table in step 4 of Work Aid 2A).
h. Press F2 to calculate the valve sizing information. Record the calculated Cv. 2. Use the following procedures to complete part 2.
a. Locate the page in Fisher Catalog 10 that describes the valve that is specified. Ensure that you locate the page that lists capacities for the appropriate line-to- body size ratio.
b. Select a valve size that provides the maximum required Cv at a percentage of travel (or degrees of rotation) that is consistent with Section 5.2 of SAES-J- 700. (Refer to the table in part 2 of Work Aid 1A.)
c. Record the information that is requested in the Exercise. 3. Use the following procedures to complete part 3.
a. Locate the page in Fisher Catalog 10 that describes the valve that is specified. Ensure that you use the page that lists capacities for the appropriate line-to- body size ratio.
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4. Use the following procedures to complete part 4.
a. Press ESCAPE to return to the menu that gives choices of sizing methods. b. Select the ISA Liquid sizing method.
c. From the menu that appears, select the Valve Sizing and LpA option.
d. Press F3. Ensure that the options Calculate FP, Viscous Correction OFF, and Input Pv, are selected.
e. Ensure that fluid properties and the service conditions are accurately entered. f. Enter an estimated FL. Determine an estimated value of FL through the use of
the equation that follows or by selecting a value from the table below. Estimated FL = Estimated Km
Typical Values Of Km and FL
Valve Style Typical Km Typical FL
Globe And Angle 0.75 .87
Rotary-Shaft 0.45 0.67
g. Enter an assumed valve inlet size, d. Use the valve size that was previously selected.
h. Enter the appropriate values for D1 and D2.
i. Press F2 to calculate the valve sizing information. Record the value of Cv. j. Select an appropriate valve size. Note: Because the calculated Cv includes the
necessary correction for piping factors, ensure that you select a valve size from the table that lists capacities for a 1:1 line-to-body size ratio. Also, ensure that you select a valve size that is consistent with the percentage of travel guidelines that are listed in Section 5.2 of SAES-J-700. (Refer to the table in part 2 of Work Aid 1A.)
Work Aid 2E: Procedures Used To Computer Size Control Valves With Viscosity Correction
1. Use the following procedures to complete part 1.
a. Press ESCAPE to return to the menu that gives choices of sizing methods. b. Select the Fisher Liquid sizing method.
c. Press and hold the ALT key, and press F5 to clear any sizing inputs. d. Select the Valve Sizing and LpA option.
e. Press F3. Ensure that the options Viscous Correction OFF and Input Pv are selected.
f. Enter the fluid name.
g. Ensure that the engineering units that are displayed on the calculation screen match the units that are used in the description of the application. If necessary, change the units for any field by moving the cursor to the field, pressing F8, and selecting the desired units.
h. Enter the fluid properties and the service conditions.
i. Enter an estimated value of Km. (Refer to the table in part 4 of Work Aid 2A.) j. Press F2 to calculate the valve sizing information.
k. Locate the page in Fisher Catalog 10 that describes the valve that is specified in the Exercise.
l. Select a valve size that satisfies the Cv requirement according to the travel guidelines that are given in Section 5.2 of SAES-J-700. (Refer to the table in part 2 of Work Aid 1A.)
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2. Use the following procedures to complete part 2. a. Do NOT clear the calculation screen.
b. Press F3. Ensure that the options Input Pv, and Viscous Correction ON are selected.
c. Ensure that the engineering units that are displayed on the calculation screen match the units that are used in the description of the application. If necessary, change the units for any field by moving the cursor to the field, pressing F8, and selecting the desired units.
d. Ensure that all fluid properties and service conditions are accurately entered. e. Press F2 to calculate the valve sizing information.
f. Refer to the appropriate page in Fisher Catalog 10, and select a valve size that satisfies the Cv requirement according to the travel guidelines that are given in Section 5.2 of SAES-J-700. (Refer to the table in part 2 of Work Aid 1A.) g. Record the requested values.
3. Use the following procedures to complete part 3. a. Do NOT clear the calculation screen.
b. Press ESCAPE twice to return to the sizing methods menu. c. Select the ISA Liquid sizing method.
d. From the menu that appears, select the Valve Sizing and LpA option.
e. Press F3. Ensure that the options Omit FP, Viscous Correction ON, and Input Pv are selected.
f. Note that the software may have calculated a value of FL from the Km that was included in the previous calculation. If the software has not calculated this value, calculate FL from the value of Km that was used previously; i.e., FL = square root of Km. Alternatively, an estimated value of FL may be obtained from the table that is included in part 4 of Work Aid 2A.
g. Enter the appropriate value of Fd for a globe valve. To view a Help Screen that explains Fd values, press the F1 key twice, press "v" to view a list of valve sizing Help Screens, select Valve Sizing: Sizing Parameters, and press Page Down until the explanation of Fd appears. (Note that for most globe valves, Fd = 1.0).
h. Assume that the valve size is equal to the line size, and enter an appropriate value for d.
i. Press F2 to calculate the valve sizing information, and note the Cv.
j. Refer to Fisher Catalog 10, and ensure that the valve size that is assumed above can provide the required capacity. If it appears that a smaller valve can provide the need capacity, change the value of d, calculate Cv, and again refer to the sizing tables. Ensure that you select a valve that is consistent with the guidelines in Section 5.2 of SAES-J-700 (see the table in part 2 of Work Aid 1A).
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Work Aid 2F: Procedures That Are Used To Computer Size Control Valves With Viscosity And Piping Factor Correction
1. Use the following procedures to complete part 1.
Calculating Cv with Viscous Correction
a. Press ESCAPE until the valve sizing method menu appears. b. Select the ISA Liquid sizing method.
c. Clear all values by pressing ALT-F5. d. Select the Valve Sizing and LpA option.
e. Press F3. Ensure that the options Omit FP, Viscous Correction ON and Input Pv are selected.
f. Ensure that the engineering units that are displayed on the calculation screen match the units that are used in the description of the application. If necessary, change the units for any field by moving the cursor to the field, pressing F8, and selecting the desired units.
g. Enter the fluid properties and the service conditions.
h. Enter an estimated value of FL. An estimated value of FL can be obtained from the table in part 4 of Work Aid 2A.
i. Enter the appropriate value of Fd. Refer to step g. in part 3. of Work Aid 2E. j. Assume that the valve size is equal to the line size, and enter the appropriate
value for d.
k. Press F2 to calculate the valve sizing information, and note the Cv.
l. Refer to the appropriate page in Fisher Catalog 12, and select a control valve size that provides the required Cv at a percentage of travel that is consistent with Section 5.2 of SAES-J-700. Refer to the table in part 2 of Work Aid 1A. m. Record the selected valve size and the degrees of rotation at which the valve
Calculating Cv with Piping Factor Correction
a. Press F3. Ensure that the options Calculate FP and Viscous Correction OFF are selected.
b. Initially assume that the required valve size is equal to line size, and enter the